Photographic stencil



Patented May 8, 1951 PHOTOGRAPHIC STENCIL Charles D. Tate and Bruce E. Gramkee, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey N Drawing. Application July 25, 1946, Serial No. 686,161

11 Claims.

This invention relates to stencils and more particularly to an improved stencil for use as a photographic negative.

In the production of a number of photographic prints for educational or illustrative purposes, it is frequently necessary to include titles and other information on the prints. The best method of putting this information on a plurality of prints is by photography. This has been accomplished heretofore by employing in conjunction with a continuous tone negative, a photographic line negative made from a typed or hand lettered original or it may be done by employing a composite stencil sheet material similar to that used in producing mimeograph stencils except that the-sheet is relatively opaque to the wave lengths of light to which photographic paper is sensitive. Essentially, this composite stencil sheet is made irom a sheet of paper such as Japanese rice paper that is coated and impregnated with a wax-pigment-dye layer which is relatively opaque to blue light. The pressure of the type pushes the wax aside and the paper fiber holds the letters together. Such a material produces a satisfactory negative when used in a tyepwriter but has the disadvantage of being flimsy and easily torn, sticky at summer temperatures, and sensitive to the typing pressure used in cutting the stencil. Because of its delicate physical characteristics, each composite stencil sheet requires a rigid carrier sheet with the guide lines for typing directly on the material.

An object, therefore, of the present invention is a rugged stencil sheet adapted for use as a photographic negative which may be employed without I" an associated permanent carrier sheet.

Another object of the invention is a transparent sheet which can be loosely attached to a temporary carrier sheet on which are printed guide lines for typing as contrasted with the common practice of making typing stencils with guide lines printed on the stencil.

A further object of the invention is a stencil sheet which does not transfer materials from itself to the photographic film or other photosensitive material.

Still another object is a non-sticky stencil sheet which permits stacking or rolling adjacent stencils together without blocking. Other objects will be apparent hereinafter.

In accordance with one feature of the invention, these and other objects are attained by forming a photographic stencil from two thin transparent sheets of a plastic material laminated to an inner layer of a wax-like material containing an opaquing substance. The wax-like inner layer with its opaquing substance should be sufficiently opaque to light so that it will present exposure of the photosensitive element when placed therecver and subjected to light. The opaque wax layer, however, should take the impression of a typewriter type or a stylus when impressed against the outer transparent plastic sheet and be sufiiciently displaced by this pressure to reduce the opacity of the composite sheet at that point so as to permit light to pass through the impression to the photosensitive film or other such element. Corrections may be made by redistributing the wax layer with a stylus hav ing a rounded end.

The wax-like layer capable of taking the impression of a typewriter key or stylus need be no thicker than is necessary to take the impression and provide sufficient opacity to enable photomay be used alone or in combination with the dyes.

The invention is further illustrated in the following examples:

Example 1 Two thin sheets of unplasticized cellulose triacetate coated on one side with a thin layer of So-cony wax #2310 (an aliphatic-hydrocarbon wax, known as a microcrystalline wax, having a minimum melting point of F., needle penetration 25-35) and containing National Aniline Oil Yellow #2681 (which corresponds to aminoazotoluene and its hydrochloride) are laminated together by pressure so as to cause the wax layers to form an interlayer between the two sheets. This opaque wax interlayer is capable of being displaced by the pressure of type or stylus. The laminated stencil sheet is now placed in a typewriter with or without a carrier sheet and typed on in the usual manner taking care that uniform pressure is used on all keys. This stencil carrying the impre..- on, of the type, is then placed in intimate contact with a sheet of A20 or Kodabromide paper and exposed. The resulting photographic print is sharp and clear.

Example 2 Two sheets of transparent cellulose acetate each coated on one side with Socony #2305 wax (which is an aliphatic-hydrocarbon wax, known as a microcrystalline wax, melting point 155 min., needle penetration 25-35, color Lovibond 30-40, Saybolt viscosity 210 '70 sec., and flashpoint l60 F.) containing 1% Oil Red 4 B were laminated to form an opaque stencil sheet. Tyewriting on this sheet was reproduced perfectly on a photographic film by permitting light to pass through the impression of the type letters to the film positioned thereunder.

The thin plastic sheets, as indicated in the above examples, may be made by known sheet forming processes from cellulose esters such as cellulose acetate, cellulose triacetate, cellulose acetate butyrate, cellulose propionate, cellulose acetate propionate, regenerated cellulose, vinyl resins or other known plastics having sufficient strength and toughness and transparency. In general, such sheets are available on the market in desirable dimensions. The thickness of these sheets should be no greater than is necessary to give the desired strength. We have found that a stencil made from cellulose triacetate or cellulose acetate butyr-ate sheets having a thickness of 0.0006 inch is satisfactory. However, the individual sheets may have thicknesses within the range of 0.0005 to .00150 inch.

Various waxes or wax-like materials may be employed as the interlayer between the thin plas tic sheets. Materials such as microcrystalline Waxes, water soluble synthetic waxes, and natural waxes, or such waxes compounded with plasti- 'cizers and resins can be employed for this layer. Among those giving particularly good results are beeswax, and the amorphous wax known as s ocony #2310.

( Some of the dyes which may be used with natural and parafiin type waxes are the CGIIIXIlOllwealth Dye and Color Co.s Oil Red i B, Coine Vale Oil Red, National Aniline Oil Yellow #2081, Heller 8; Merz Calco Phenyl Red Y, Oil yellow 2 G and Grasol Yellow R. With water soluble waxes, water soluble dyes such as Tartrazine are satisfactory. Mixtures of dye may be required to obtain satisfactory spectral out. These dyes are soluble in the above described waxes but will not travel from the wax into the plastic sheets. Pi ments may be used alone or in combination with the dyes. The transparent pigments are preferred so as to avoid complete opacity in the sheet, for exampla cadmium yellow pale, burnt sienna, raw sienna, iron oxide, etc.

'Ifhe composite photographic stencil negative may be assembled by any suitable coating and laminating method known to the art such as applying in a continuous operation, the molten 1m. pression taking layer to one sheet as it passes around a roll immersed in the molten bath and then laminating the second sheet by means of a squeeze roll located above the cooled roll. The thickness of the impression taking layer is controlled by a suitable scraper-bar, doctor rolls or a wire such as used on a Mayer laminating machine.

We have found our novel photographic stencil sheet is very satisfactory for photographic duplication of written and typed matter, and because of its ruggedness can be employed many times with perfect reproduction.

We claim: W

' l. A laminated stencil sheet comprising a pair of thin transparent plastic sheets having a pressure deformable wax-like interlayer therebetween, said layer being normally opaque to light, but capable of transmitting sufficient light to expose a photosensitive element at places when the layer is thinned by pressure means applied only to the exterior of one of said transparent sheets.

2. A. laminated stencil sheet comprising a pair of thin transparent cellulose ester sheets having a pressure deformable wax-like interlayer therebetween, said layer being normally opaque to light, but capable of transmitting sufficient light to expose a photosensitive element at places when the layer is thinned by pressure means applied only to the exterior of one of said trans parent sheets.

3. A laminated stencil sheet comprising a pair of thin transparent cellulose acetate butyrate sheets having a pressure deformable wax-like interlayer therebetween, said layer being normally opaque to light, but capable of transmit tingsuflicient light to expose a photosensitive element at places when the layer is thinned by pressure means applied only to the exterior of one of said transparent sheets.

- 4. A. laminated stencil sheet comprising a pair of thin transparent cellulose triacetate sheets having a pressure deformable wax-like interlayer therebetween, said layer being normally opaque to light, but capable of transmitting suificient light to expose a photosensitive element at places when the layer is thinned by pressure means applied only to the exterior of one of said transparent sheets.

5. A laminated stencil sheet comprising a pair of thin transparent cellulose acetate sheets having a pressure deformable wax-like interlayer therebetween, said layer being normally opaque to light, but capable of transmitting sufiicient light to expose a photosensitive element at places when the layer is thinned by pressure means applied only to the exterior of one of said transparent sheets.

6. A laminated stencil sheet comprising a pair of thin transparent vinyl resin sheets having a pressure deformable wax-like interlayer therebetween, said layer being normally opaque to light, but capable of transmitting sufficient light to expose a photosensitive element at places when the layer is thinned by pressure means applied only to the exterior of one of said transparent sheets.

"7. A laminated stencil sheet comprising a pair of thin transparent regenerated cellulose sheets having a pressure deformable wax-like intcrlayer therebetween, said layer being normally opaque to light, but capable of transmitting sufiicient light to expose a photosensitive element at places when the layer is thinned by pressure means applied only to the exterior of one of said transparent sheets.

8. A laminated stencil comprising a pair of transparent cellulose organic acid ester sheets of a thickness of approximately 0.0006 inch having an opaque pressure deformable interlayer therebetween comprising a microcrystalline wax composition having a minimum melting point of -F. and a needle penetration of 25-35, said interlayer only being capable of transmitting sufficient light to expose a photosensitive film at places where the interlayer is thinned by pressure means applied only to the exterior of one of said transparent sheets as by the type'of a typewriter, and being capable of retaining the shape of the pressure means under normal conditions of use.

9. A laminated stencil comprising a pair of transparent cellulose triacetate sheets of a thickness of approximately 0.0006 inch having an opaque pressure deformable interlayer therebetween compriisng a miorocrystalline wax composition having a minimum melting point of 155 F. and a needle penetration of 25-35, said interlayer only being capable of transmitting sufflcient light to expose a photosensitive film at places where the interlayer is thinned by pressure means applied only to the exterior of one of said transparent sheets as by the type of a typewriter, and being capable of retaining the shape of the pressure means under normal conditions of use.

10. A laminated stencil comprising a pair of transparent cellulose acetate sheets of a thickness of approximately 0.0006 inch having an opaque pressure deformable interlayer therebetween comprising a miorocrystalline wax composition having a minimum melting point of 155 F. and a needle penetration of 25-35, said interlayer only being capable of transmitting sufficient light to expose a photosensitive film at places where the interlayer is thinned by pressure means applied only to the exterior of one of said transparent sheets as by the type of a typewriter, and being capable of retaining the shape of the pressure means under normal conditions of use.

11. A laminated stencil comprising a pair of transparent cellulose acetate butyrate sheets of a thickness of approximately 0.0006 inch having an opaque pressure deformable interlayer therebetween comprising a miorocrystalline wax composition having a minimum melting point of F. and a needle penetration of 25-35, said interlayer only being capable of transmitting sufficient light to expose a photosensitive film at places where the interlayer is thinned by pressure means applied only to the exterior of one of said transparent sheets as by the type of a typewriter, and being capable of retaining the shape of the pressure means under normal conditions of use.

CHARLES D. TATE. BRUCE E. GRAMKEE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,090,240 Scritsmeir Mar. 17, 1914 1,266,766 Brandenberger May 21, 1918 2,016,599 Graves Oct. 8, 1935 2,129,456 Wynd et a1. Sept. 6, 1938 2,140,506 Canning Dec. 20, 1938 2,240,072 Hodgdon et al. Apr. 29, 1941 2,296,171 Magill Sept. 15, 1942 2,402,870 Burgess et a1. June 25, 1946 2,402,903 Massey et al. June 25, 1946 

8. A LAMINATED STENCIL COMPRISING A PAIR OF TRANSPARENT CELLULOSE ORGANIC ACID ESTER SHEETS OF A THICKNESS OF APPROXIMATELY 0.0006 INCH HAVING AN OPAQUE PRESSURE DEFORMABLE INTERLAYER THEREBETWEEN COMPRISING A MICROCRYSTALLINE WAX COMPOSITION HAVING A MINIMUM MELTING POINT OF 155* F. AND A NEEDLE PENETRATION OF 25-35, SAID INTERLAYER ONLY BEING CAPABLE OF TRANSMITTING SUFFICIENT LIGHT TO EXPOSE A PHOTOSENSITIVE FILM AT PLACES WHERE THE INTERLAYER IS THINNED BY PRESSURE MEANS APPLIED ONLY TO THE EXTERIOR OF ONE OF SAID TRANSPARENT SHEETS AS BY THE TYPE OF A TYPEWRITER, AND BEING CAPABLE OF RETAINING THE SHAPE OF THE PRESSURE MEANS UNDER NORMAL CONDITIONS OF USE. 